Double Cylinder Type Hydraulic Mechanism

ABSTRACT

A hydraulic mechanism includes an outer cylinder having an expansion side working port and a contraction side working port respectively formed on a top of the outer cylinder; an inner cylinder insertedly installed inside the outer cylinder to come in and out toward a bottom of the outer cylinder; an inner rod having two flow paths respectively connected to the expansion side working port and the contraction side working port, one end of which is fixed to an inner top surface of the outer cylinder, and the other end of which passes through a top of the inner cylinder and protrudes to be positioned inside the inner cylinder; and a piston combined with the other end of the inner rod to be positioned inside the inner cylinder and formed with a hole connected to the flow path of the inner rod connected to the expansion side working port.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit and priority of Korean PatentApplication No. 10-2011-0007153 filed Jan. 25, 2011, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic mechanism using hydraulicpressure as a power source, which is capable of supporting weight of aplatform (or a mounted structure) in the vertical direction of acylinder and moving the platform to a desired position. Moreparticularly, the present invention relates to a double cylinder typehydraulic mechanism, which is constructed to normally operate withoutleakage of hydraulic pressure and working fluid to outside in a poorenvironment in which a large amount of lateral loads are applied due tomodification of the mounted platform or a ground slope, or working partsof the cylinder exposed to outside can be easily damaged because of thesurface corroded by contaminated materials such as flames or propellantgas or scratched by bounce of stones.

2. Background of the Related Art

Generally, since a hydraulic mechanism (particularly, a hydraulic jack)has a powerful output per unit weight and a simple structure, it isfrequently used at a site of a poor working environment, such as aground structure work site or a public work site.

FIG. 2 shows vertical cross-sectional views for describing workingprinciples of a conventional hydraulic mechanism, particularlyprinciples of a hydraulic jack.

-   -   1. As shown in FIG. 2, the conventional hydraulic jack includes        a cylinder 201 penetratingly combining an expansion side working        port 205 at an upper side of the cylinder surface and a        contraction side working port 206 at a lower side of the        cylinder surface; a piston 202 inserted inside the cylinder 201        so as to move in the direction pushed by working fluid when the        working fluid is supplied inside the cylinder 201; a rod 203        formed or mounted at the center of any one surface of the piston        202 in one piece to expose one end of the rod to outside of the        cylinder 201; a foot plate 204 installed at the one end of the        rod 203; a piston seal 207 insertedly fixed to the outer surface        of the piston 202, for sustaining lateral loads applied in the        radius direction of the cylinder 201 and preventing leakage of        the working fluid; and a cylinder seal 208 inserted into the        inner surface of a hole positioned on the bottom of the cylinder        201 through which the one end of the rod 203 slidingly passes.

In the configuration so constructed, for example, it is assumed that thestate shown in (b) of FIG. 2 is the initial state. If working fluid issupplied into the upper portion of the cylinder 201 through theexpansion side working port 205, the piston 202 and the rod 203 arepushed downward due to the pressure of the working fluid, and theinitial state is changed into an expansion state shown in (c) of FIG. 2.

On the contrary, if the working fluid is supplied into the lower portionof the cylinder 201 through the contraction side working port 206, thepiston 202 and the rod 203 are pushed upward due to the pressure of theworking fluid, and the initial state is changed into a contraction stateshown in (a) of FIG. 2.

If the surface of the rod exposed outside the conventional hydraulicjack is corroded by flames or toxic gas or damaged by stone chips orscratches, the cylinder seal 208 inserted in the hole positioned on thebottom of the cylinder is damaged due to movement of the rod, and thus agap is made between the inner surface of the hole positioned on thebottom of the cylinder and the surface of the rod coming in and outthrough the hole, and the working fluid leaks through the gap.

Particularly, the conventional hydraulic jack is formed to supportlateral loads using only piston seals and cylinder seals respectivelyinstalled at two positions, and thus if the loads are applied in theradius direction (lateral direction) of the cylinder, e.g., if thelateral loads are applied to the cylinder due to modification of theplatform supported by the hydraulic jack or a slope of the groundsupporting the foot plate, metallic contacts occur between the rod andthe cylinder and between the piston and the cylinder, respectively.Therefore, the cylinder seal is damaged, and the working fluid is leakedoutside the cylinder through the damaged cylinder seal, and thus thehydraulic jack may lose its function.

It is undoubted that a hydraulic jack (or a hydraulic cylinder or ahydraulic mechanism) leaking the working fluid cannot properly supportthe load of a mounted structure, and an abruptly drooping phenomenonoccurs while the hydraulic jack supports the load, and thus a seriousdanger may be incurred against safety of a worker.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide adouble cylinder type hydraulic mechanism suitable for being used in apoor working condition or environment in which damages on a rod comingin and out of a cylinder are expected. Even when a huge lateral load isapplied due to modification of a mounted structure or operation of thehydraulic mechanism on a sloped ground, functions of the hydraulicmechanism (hydraulic jack or hydraulic cylinder) may not be lostalthough the seals are damaged by metallic contacts.

To accomplish the above object, according to one aspect of the presentinvention, there is provided a double cylinder type hydraulic mechanism,which can be used for an extended period of time since working fluid isnot leaked although surfaces of working parts of the hydraulic mechanismexposed to external environments and performing vertical reciprocatingactions are corroded or scratched by using the hydraulic mechanism foran extended period of time. Particularly, metallic contacts do not occurbetween the parts even in an operation condition where excessive lateralloads are applied, and thus the hydraulic mechanism may operatenormally.

The present invention is characterized in that inner and outer cylindersare assembled to slide with each other, and contraction side andexpansion side working ports are respectively formed on the flat top ofthe outer cylinder, and then two flow paths provided at an inner rod arerespectively connected to the working ports, thereby removing pipeconnection projections formed at the upper and lower portions of thecylinder surface, which are connected to external hydraulic lines.

According to another aspect of the present invention, a load supportingseal for supporting lateral loads and a seal for preventing leakage ofworking fluid and preventing foreign materials from being flowed insidethe cylinder are respectively installed between the piston and the innercylinder and between the inner cylinder and the outer cylinder.

Further specifically, the double cylinder type hydraulic mechanismaccording to the present invention includes an outer cylinder having anexpansion side working port and a contraction side working portrespectively formed on a top of the outer cylinder; an inner cylinderinsertedly installed inside the outer cylinder so as to come in and outtoward a bottom of the outer cylinder, an inner rod having two flowpaths respectively connected to the expansion side working port and thecontraction side working port, one end of which is fixed to an inner topsurface of the outer cylinder, and the other end of which passes througha top of the inner cylinder and protrudes to be positioned inside theinner cylinder; and a piston combined with the other end of the innerrod to be positioned inside the inner cylinder and formed with a holeconnected to the flow path of the inner rod connected to the expansionside working port.

In addition, the double cylinder type hydraulic mechanism according tothe present invention preferably further includes an inner cylinder sealinstalled inside an upper hole of the inner cylinder in order to supportlateral loads applied in a radius direction of the cylinder and preventleakage of working fluid from the upper hole of the inner cylinderthrough which the other end of the inner rod slidingly penetrates; apiston seal installed on an outer surface of the piston in order tosupport the lateral loads applied in the radius direction of thecylinder and prevent leakage of the working fluid between the upper andlower spaces of the inner cylinder partitioned by the piston; and anouter cylinder seal installed on an inner surface of the outer cylinderin order to support the lateral loads applied in the radius direction ofthe cylinder and remove foreign materials attached on an outer surfaceof the inner cylinder.

In addition, as is typical, a foot plate supported on the ground isinstalled on the bottom of the inner cylinder of the double cylindertype hydraulic mechanism according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

(a), (b) and (c) of FIG. 1 are vertical cross-sectional views showingthe configuration and working principles of a double cylinder typehydraulic mechanism according to the present invention.

(a), (b) and (c) of FIG. 2 are vertical cross-sectional views showingthe configuration and working principles of a conventional hydraulicmechanism.

DESCRIPTION OF SYMBOLS

-   -   101: Outer cylinder 102: Inner cylinder    -   103: Inner rod 104: Piston    -   105: Foot plate    -   106: Expansion side working port    -   107: Contraction side working port    -   108: Inner cylinder seal    -   109: Piston seal    -   110: Outer cylinder seal    -   201: Cylinder 202: Piston    -   203: Rod 204: Foot plate    -   205: Expansion side working port    -   206: Contraction side working port    -   207: Piston seal 208: Cylinder seal

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the configuration and working principles of a doublecylinder type hydraulic mechanism according to the present inventionwill be described in detail, with reference to the accompanyingdrawings.

First, in relation to the drawings, FIG. 1 shows verticalcross-sectional views for describing the configuration and workingprinciples of a double cylinder type hydraulic mechanism according tothe present invention.

As shown in FIG. 1, the double cylinder type hydraulic mechanismaccording to the present invention includes an outer cylinder 101 havingan expansion side working port 106 and a contraction side working port107 respectively formed on the top; an inner cylinder 102 insertedlyinstalled inside the outer cylinder 101 so as to come in and out towardthe bottom of the outer cylinder 101; an inner rod 103 having two flowpaths respectively connected to the expansion side working port 106 andthe contraction side working port 107, one end of which is fixed to theinner top surface of the outer cylinder 101, and the other end of whichpasses through the top of the inner cylinder 102 and protrudes to bepositioned inside the inner cylinder 102; a piston 104 combined with theother end of the inner rod 103 and formed with a hole connected to theflow path of the inner rod 103 connected to the expansion side workingport 106; a foot plate 105 mounted on the bottom of the inner cylinder102; an inner cylinder seal 108 installed inside an upper hole of theinner cylinder 102 in order to prevent leakage of working fluid from theupper hole of the inner cylinder 102 into which the other end of theinner rod 103 is slidingly inserted; a piston seal 109 insertedlyattached to the outer surface of the piston 104 in order to preventleakage of the working fluid between the upper and lower spaces of theinner cylinder 102 partitioned by the piston 104; and an outer cylinderseal 110 installed on the inner surface of the outer cylinder 101 inorder to remove foreign materials attached on the outer surface of theinner cylinder 102. Here, the inner cylinder seal 108, the piston seal109, and the outer cylinder seal 110 also support lateral loads appliedin the radius direction of the inner and outer cylinders 101 and 102.

Meanwhile, an end of the flow path connected to the contraction sideworking port 107 of the outer cylinder 101 among the two flow pathsformed at the inner rod 103 is open toward the upper space of the innercylinder 102 partitioned by the piston 104.

Accordingly, if the working fluid is supplied to either the expansionside working port 106 or the contraction side working port 107, theinner cylinder 102 moves in the vertical direction of the outer cylinder101 inside the outer cylinder 101.

Unlike a conventional hydraulic jack constructed to supply hydraulicfluid inside a cylinder through pipe connection projections respectivelyprotruding at one side of the upper and lower portions of the cylindersurface, the double cylinder type hydraulic mechanism (or the hydraulicjack) according to the present invention is constructed to supplyworking fluid into the upper or lower space of the inner cylinder 102through either the expansion side working port 106 or the contractionside working port 107 formed on the top of the outer cylinder 101.

As a result, since projections are not formed on the surface of theinner and outer cylinders 101 and 102 according to the presentinvention, when the hydraulic mechanism is installed in mountedequipment, effects of structural interference generated by hydrauliclines (or pipes) are greatly reduced.

Furthermore, in the double cylinder type hydraulic mechanism (or thehydraulic jack) according to the present invention, working fluid issupplied inside the inner cylinder 102 through the flow paths of theinner rod 103, and the inner cylinder 102 is exposed to outside. Unlikethe conventional hydraulic jack in which the rod 203 directly contactingwith the cylinder seal 208 is exposed to a poor working environment,although the surface of the inner cylinder 102 is corroded or scratched,the working fluid does not leak through the portions related tomovements of the hydraulic mechanism since the surface of the innercylinder 102 does not contact with the inner cylinder seal 108.

Furthermore, although seals installed at two positions sustain lateralloads in the conventional hydraulic jack, the lateral loads aresustained by seals installed at three or more positions in the doublecylinder type hydraulic mechanism of the present invention, and thus thedouble cylinder type hydraulic mechanism according to the presentinvention may support further greater lateral loads although it has thesame external sizes.

According to the double cylinder type hydraulic mechanism of the presentinvention constructed as described above, working fluid does not leakalthough the inner cylinder performing vertical reciprocating actions isexposed to external environments and the surface of the inner cylinderis corroded or scratched, and metallic contact is prevented by lateralload supporting actions of the inner cylinder seal, the piston seal, andthe outer cylinder seal even in an operating condition of applyinglateral loads, and thus the double cylinder type hydraulic mechanism mayoperate normally for an extended period of time.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by theembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

1. A double cylinder type hydraulic mechanism comprising: an outercylinder 101 having an expansion side working port 106 and a contractionside working port 107 respectively formed on a top of the outercylinder; an inner cylinder 102 insertedly installed inside the outercylinder 101 so as to come in and out toward a bottom of the outercylinder 101, an inner rod 103 having two flow paths respectivelyconnected to the expansion side working port 106 and the contractionside working port 107, one end of which is fixed to an inner top surfaceof the outer cylinder 101, and the other end of which passes through atop of the inner cylinder 102 and protrudes to be positioned inside theinner cylinder 102; and a piston 104 combined with the other end of theinner rod 103 to be positioned inside the inner cylinder 102 and formedwith a hole connected to the flow path of the inner rod 103 connected tothe expansion side working port
 106. 2. The mechanism according to claim1, further comprising: an inner cylinder seal 108 installed inside anupper hole of the inner cylinder 102 in order to support lateral loadsapplied in a radius direction of the cylinder and prevent leakage ofworking fluid from the upper hole of the inner cylinder 102 throughwhich the other end of the inner rod 103 slidingly penetrates; a pistonseal 109 installed on an outer surface of the piston 104 in order tosupport the lateral loads applied in the radius direction of thecylinder and prevent leakage of the working fluid between the upper andlower spaces of the inner cylinder 102 partitioned by the piston 104;and an outer cylinder seal 110 installed on an inner surface of theouter cylinder 101 in order to support the lateral loads applied in theradius direction of the cylinder and remove foreign materials attachedon an outer surface of the inner cylinder 102.